TNF-α基因在F18大肠杆菌抗性型和敏感型断奶仔猪间的差异表达分析

本研究运用Real-time PCR方法分析TNF-α基因在苏太猪F18大肠杆菌抗性型和敏感型断奶仔猪群体中11个组织中的表达谱,以及在抗性型和敏感型个体之间的差异表达,以探讨TNF-α基因在断奶仔猪抗F18大肠杆菌感染中的作用。结果表明:TNF-α基因在抗性型和敏感型个体所检测的11个组织中均有表达,其中在脾脏、肺、肾脏、胸腺和淋巴结组织中表达量较高,在十二指肠和空肠组织中呈中度表达;TNF-α基因在F18大肠杆菌抗性型个体各个组织中的表达量普遍高于敏感型个体,且脾脏、肾脏、胸腺和十二指肠组织中TNF-α基因在抗性型个体中的表达量显著高于敏感型个体(P0.05)。由此推测,TNF-α基因的较高表达可能有利于提升仔猪对F18大肠杆菌的抵抗能力,在F18大肠杆菌侵袭后引起的一系列免疫应答过程中发挥着重要的作用。     

HSP27基因在苏太猪F18大肠杆菌抗性型和敏感型个体间的差异表达分析

热休克蛋白27(heat shock protein 27,HSP27)是哺乳动物普遍存在的小休克蛋白家族成员之一,在参与调解细胞的增殖、分化和细胞凋亡过程中起到了重要的作用。为探讨猪HSP27基因的表达水平及其与F18大肠杆菌抗性的关系,本研究运用荧光定量PCR方法检测HSP27基因在苏太猪F18大肠杆菌病抗性型和敏感型资源群体中各组织的表达水平,并分析在E.coli F18抗性组和敏感组中的表达差异。结果表明:HSP27基因在所有检测个体的11个组织中均有表达,其中肺中表达量最高,其次在肝、脾、肾、十二指肠和空肠中表达较高,而在肌肉、胸腺和淋巴结中表达较低;抗性组和敏感组差异表达显示,在肝脏和淋巴结2个组织中,HSP27基因在抗性组个体中的表达量极显著高于敏感性个体的表达量(P0.01),在脾脏、胸腺和空肠3个组织中,HSP27基因在抗性组个体中的表达量显著高于敏感性个体的表达量(P0.05)。HSP27基因在E.coli F18抗性组免疫组织和肠道组织中的高水平表达提示HSP27基因可能在机体抵抗F18大肠杆菌感染过程中发挥了重要的免疫调控作用。     

F18大肠杆菌抗性型与敏感型苏太断奶仔猪十二指肠组织比较转录组分析

旨在揭示培育品种—苏太猪(杜洛克×梅山猪)F18大肠杆菌抗性的调控通路和重要候选基因,同时进一步探究中外猪品种F18大肠杆菌抗性调控遗传基础的差异。本研究以课题组前期获得的苏太猪和梅山猪F18大肠杆菌抗性型与敏感型断奶仔猪全同胞个体为研究对象,通过转录组测序筛选苏太猪F18大肠杆菌抗性相关的调控通路以及重要候选基因,并在细胞水平,利用qPCR和Western blot分析F18大肠杆菌刺激小肠上皮细胞IPEC-J2后重要候选基因(蛋白)的表达变化,同时利用qPCR检测重要候选基因在苏太和梅山断奶仔猪F18大肠杆菌抗性型与敏感型个体十二指肠组织中的差异表达情况。结果显示:1)在苏太断奶仔猪F18大肠杆菌抗性型与敏感型个体中筛选出238个差异表达基因,主要参与Toll样受体信号通路(toll-like receptor signaling pathway)和糖脂类通路(glycosphingolipid biosynthesis-lacto and neolacto series),其中TLR5、IL-1β、FUT2为重要候选基因;2)不同血清型F18大肠杆菌(F18ac、F18ab)菌体分别刺激小肠上皮细胞IPEC-J2后,FUT2、IL-1β、TLR5基因mRNA表达水平显著上调(P0.05),并且其蛋白表达水平也表现为明显的上调,由此表明,TLR5、IL-1β和FUT2在断奶仔猪F18大肠杆菌感染过程中发挥重要的调控作用;3)组织差异表达分析显示,TLR5、IL-1β和FUT2在苏太猪抗性型与敏感型个体十二指肠组织中表达差异均达到显著水平(P0.05),而梅山猪中TLR5、IL-1β表达差异达到极显著水平(P0.01),FUT2表达水平差异不显著(P0.05)。结合课题组前期关于梅山猪及外来引进品种F18大肠杆菌抗性相关分子机制研究及报道,本研究进一步证明中外猪品种F18大肠杆菌抗性调控的遗传基础确实存在差异,Toll样受体信号通路及CD14、TLR5等基因可能在中国地方品种—梅山猪抵抗F18大肠杆菌感染过程中发挥着免疫调控作用,而鞘糖脂合成通路及FUT2等基因可能在外来猪品种F18大肠杆菌受体形成过程中起关键作用。     

LTβR基因在大肠杆菌F18抗性型和敏感型苏太仔猪间的差异表达分析

旨在探讨LTβR基因在苏太断奶仔猪各组织间的mRNA表达谱,并比较分析该基因在大肠杆菌F18抗性/敏感型群体间的表达差异,为进一步探讨该基因的功能及筛选断奶仔猪大肠杆菌F18抗性遗传标记提供一定的指导和依据。试验分别挑选35日龄大肠杆菌F18抗性/敏感型苏太断奶仔猪各4头,利用实时荧光定量PCR方法比较分析LTβR基因在11个组织(心、肝、脾、肺、肾、胃、肌肉、胸腺、淋巴结、十二指肠、空肠)间的表达差异。结果:LTβR基因在检测的11个组织中均有表达,其中在肝、肺、肾、胃、十二指肠和空肠呈现高水平表达,在脾和淋巴结中呈现中等水平表达,在心脏、肌肉和胸腺组织中呈现低水平表达。除肝脏外,LTβR基因在抗性型个体中表达量普遍高于敏感型个体,而且在肠系膜淋巴结中的表达量极显著高于敏感型个体(P0.01)。由此推测,LTβR基因的表达上调有利于断奶仔猪抵御大肠杆菌F18的感染,且可能是通过在淋巴结组织中的高表达维持和提高了肠道的免疫水平,从而提高了断奶仔猪抵御大肠杆菌F18感染的能力。     

MUC4和MUC13基因在ETECF18抗性型和易感型梅山断奶仔猪间的差异表达分析

MUC4和MUC13基因作为产肠毒素大肠杆菌(enterotoxigenic Escherichia coil,ETEC)F4的重要抗性候选基因,可能在断奶仔猪抗ETEC F18菌株的感染过程中发挥重要作用,因此本试验运用实时荧光定量PCR法分析了MUC4和MUC13基因在梅山猪ETEC F18抗性型和易感型个体11个组织(心脏、肝脏、脾脏、肺脏、肾脏、胃、肌肉、胸腺、淋巴结、十二指肠和空肠)中的表达水平及差异。结果显示,MUC4和MUC13基因在检测的11个组织中均有不同程度的表达。其中,在胸腺和淋巴组织中,MUC4基因在抗性型个体中的表达水平显著高于易感型个体(P0.05);在肺脏组织中,MUC13基因在抗性型个体中的表达水平显著高于易感型个体(P0.05),且MUC13基因在抗性群体肠道中的表达水平较高。由此推测,MUC4基因在免疫组织、MUC13基因在肠道组织的高表达可在一定程度上提高了机体的免疫能力,保护和润滑肠道,从而抵抗ETEC F18菌株对机体的感染。     

CD14基因在大白猪F18大肠杆菌病耐受型和敏感型个体间的差异表达分析

本研究旨在分析CD14基因在大白猪F18大肠杆菌耐受型和敏感型个体间的mRNA表达差异,以探讨CD14基因在断奶仔猪抗F18大肠杆菌中发挥的潜在作用。挑选大白猪耐受型和敏感型个体各4头,通过利用Real-time PCR方法比较分析CD14基因在个体各组织间的表达规律。结果表明:CD14基因在大白猪耐受型和敏感型个体各组织间的表达趋势有着高度的一致性,其中CD14基因在肝中呈现高水平表达,在肺、肾和淋巴结中呈现中度表达,而在其他组织中的表达水平都非常低,CD14基因在耐受型个体各组织间的表达水平几乎都高于敏感组,其中CD14基因表达量在空肠组织中差异达到极显著水平(P0.01)。由此推测,CD14基因对E.coli F18抗性的调节可能不是通过直接作为F18大肠杆菌的受体来实现,而是通过参与并调节机体的免疫反应来实现的,并且CD14基因的上调可能与F18大肠杆菌的抗性存在一定的联系。     

SLA-DQA基因在F18大肠杆菌抗性和敏感性断奶仔猪间的差异表达分析

运用荧光定量PCR方法分析SLA-DQA基因在苏太猪F18大肠杆菌病抗性和敏感性资源群体中各个组织的分布和表达水平,以及在抗性组和敏感组中的表达差异,以探讨SLA-DQA基因在断奶仔猪抗大肠杆菌F18菌株感染中发挥的作用。试验结果显示,SLA-DQA基因在所检测的11个组织中均有表达,并呈现相似的表达规律,在肺、脾和淋巴结中的表达量较高,在空肠、十二指肠和胸腺中也有中度的表达。SLA-DQA基因在抗性组个体各个组织中的表达量普遍高于敏感性个体,而且在肺、脾、淋巴结、空肠和十二指肠5个组织中,SLA-DQA基因在抗性组个体中的表达量显著高于敏感性个体(P<0.05)。由此可见,当断奶仔猪受到大肠杆菌毒素侵扰后,SLA-DQA基因较高的表达量有利于SLA-II类抗原分子的合成,SLA-DQA基因虽然不是针对由大肠杆菌F18菌株造成的断奶仔猪腹泻和水肿病的直接免疫因子,但是在断奶仔猪受大肠杆菌F18菌株病原菌侵袭后引起的一系列生理变化和应答过程中发挥着重要的作用。     

TLR5基因启动子区甲基化修饰与苏太断奶仔猪E. coli F18抗性的关系

旨在分析探讨TLR5基因启动子区甲基化修饰对断奶仔猪F18大肠杆菌抗性的调控作用。本研究首先利用qPCR和Western blot检测分析了TLR5基因在F18大肠杆菌抗性型和敏感型苏太断奶仔猪小肠组织(十二指肠和空肠)中的差异表达,然后利用生物信息学分析和双荧光素酶报告系统检测确定TLR5基因核心启动子区、CpG岛及其作用元件,进而检测并分析TLR5基因启动子区甲基化修饰与TLR5基因在F18大肠杆菌抗型和敏感型断奶仔猪小肠组织中表达水平的相关性。结果表明,TLR5基因在敏感型断奶仔猪十二指肠和空肠组织中的mRNA表达水平分别显著(P0.05)和极显著(P0.01)高于在抗性型个体中的表达,且十二指肠和空肠组织中敏感组蛋白表达水平均显著高于抗性组(P0.05)。TLR5基因启动子区包含2个CpG岛和16个作用元件,启动子区第2个CpG岛第6个CG位点甲基化水平对TLR5基因的表达具有一定的调控作用,该位点位于转录因子Sp1结合的核心启动子区域。本研究结果表明,猪TLR5基因的表达水平和F18大肠杆菌的抗性有关,其低表达可能有利于F18大肠杆菌抗性;TLR5基因启动子区第2个CpG岛第6个CG位点甲基化能够显著抑制TLR5基因的表达,并最终影响断奶仔猪对大肠杆菌的抗性。     

猪m6A去甲基化酶FTO、ALKBH5基因表达水平与大肠杆菌F18感染抗性的关系分析

为了探讨猪6-甲基腺嘌呤（m⁶A）去甲基化酶mRNA表达水平与仔猪大肠杆菌F18抗性的关系,本研究运用实时荧光定量PCR方法检测m⁶A去甲基化酶FTO和ALKBH5基因在35日龄苏太猪断奶仔猪大肠杆菌F18抗性型和敏感型个体十二指肠和空肠组织中的mRNA表达差异,同时分别利用F18ab、F18ac大肠杆菌菌体刺激和内毒素LPS诱导猪小肠上皮细胞（IPEC-J2）,检测FTO、ALKBH5基因表达变化。结果表明,FTO、ALKBH5基因在抗性型个体十二指肠和空肠中的表达量均极显著或显著高于敏感型个体（P<0.01,P<0.05）;不同F18大肠杆菌菌体刺激IPEC-J2细胞后,FTO基因表达水平均无显著变化（P>0.05）,而ALKBH5基因在F18ac刺激后表达量显著上调（P<0.05）;LPS诱导4 h时,FTO和ALKBH5基因表达量均显著上调（P<0.05）。本研究在细胞和个体水平上初步验证并发现了m⁶A去甲基化酶FTO和ALKBH5基因表达水平与大肠杆菌感染仔猪密切相关,为今后深入研究RNA去甲基化修饰在仔猪细菌性腹泻调控中的作用机制提供了理论基础。     

SLA-DQA基因在大约克、苏太和梅山猪断奶仔猪中组织表达差异分析

本研究旨在通过对SLA-DQA基因在苏太猪大肠杆菌F18菌株抗性群体和大约克猪、梅山猪断奶仔猪各组织间的表达规律及其在3个群体间表达差异的分析,探讨SLA-DQA基因与国内外猪品种断奶仔猪不同水平免疫机能和大肠杆菌抗性间的潜在关系。研究结果显示,SLA-DQA基因在3个猪群体所检测的11个组织中均表达,并且表达规律基本一致,在肺脏、脾脏、淋巴结等免疫器官中的表达量较高,在胃、十二指肠、空肠等消化道中表达量居中。SLA-DQA基因在苏太猪所有检测组织中的表达量均最高,大约克中次之,梅山猪中表达量最低。尤其在肺脏、淋巴结和胸腺3个组织中,SLA-DQA基因在苏太猪中的表达量均显著高于其在梅山猪中的表达量;在胸腺组织中,SLA-DQA基因在苏太猪中的表达量显著高于大约克猪。研究结果表明,SA-DQA基因在断奶仔猪受大肠杆菌F18菌株病原菌侵袭后引起的一系列生理变化和应答过程中发挥着重要的抗原递呈和激发机体免疫的作用。     

白术、微米白术和白术多糖对断奶仔猪生长性能和肠道形态及微生态区系的影响

试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Y‐chromosomal variation of local goat breeds of Turkey close to the domestication centre

Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.     

Changes in proportion of canine urinary calculi composed of calcium oxalate or struvite in specimens analyzed from 1981 through 2001

The objective of this report was to characterize 20-year changes in proportion of calcium oxalate (CaOx) calculi and struvite calculi in dogs, and associations with breed, age, and sex. In this retrospective study, results of analysis of urinary calculi from dogs were reviewed for specimens received between July 1, 1981, and December 31, 2001. Breed, sex, age, year of submission of the specimen, and mineral type(s) were analyzed statistically. CaOx or Struvite or both were contained in 18,966 of 20,884 (91%) specimens. For both sexes, a 20-year statistically significant increase was observed in the proportion of calculus specimens that contained CaOx. The increase in this proportion was greater in females (1% to 31%) than in males (18% to 82%). From 1998 to 2001, when proportions may have plateaued, the odds of specimens containing CaOx were markedly higher in 18 breeds, markedly lower in 5 breeds, and not significantly different in 13 breeds compared with crossbreds. For both sexes, a 20-year statistically significant decrease was observed in the proportion of calculus specimens that contained struvite. This decrease in proportion was greater for males (79-16%) than for females (97-68%). From 1998 to 2001, when proportions plateaued, the odds of calculi containing struvite were markedly lower in 20 breeds, markedly higher in 1 breed, and not significantly different in 15 breeds when compared with crossbreds. Breed, age, and sex were associated statistically with CaOx or struvite urolithiasis. In conclusion, there appears to have been a long-term increase in the proportion of specimens of canine urinary calculi that contain CaOx as well as a long-term decrease in the proportion of specimens of calculi that contain struvite for both male and female dogs. The rate of change appeared to begin leveling off in the period 1998 to 2001. The recent proportion of dogs with either CaOx- or struvite-associated urolithiasis may depend on breed, age, and sex, and on interactions among these 3 factors.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.